Pressure activated cyclical valve apparatus and method

ABSTRACT

A pressure activated cyclical valve assembly includes a first sub, a second sub, a piston, and a biasing member. The first sub has a first passageway therethrough. The second sub is coupled to the first sub and has a second passageway therethrough. The piston is positioned within the second passageway and is shiftable between a deactivated position in which a bypass port is closed and an activated position in which the bypass port is open. The piston has a piston orifice and the first passageway is in fluid communication with the second passageway through the piston orifice. The biasing member exerts a force against the piston to maintain the piston in the deactivated position. The piston orifice is sized to restrict the flow of fluid therethrough such that the piston can be shifted between the deactivated and activated positions by changing flowrate of fluid in the first passageway.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 62/459,377, filed Feb. 15, 2017, the entirety of which is incorporated herein by reference.

BACKGROUND

During the drilling, work over, or plug and abandonment of oil and gas producing wells, a variety of downhole tools may be attached to a pipe or coiled tubing string and utilized to perform various functions within the wellbore. Often, the need arises to divert a portion of the fluid that is flowing within the downhole tool string so that the fluid bypasses the tool string and is directed to within the wellbore. Diverting the fluid allows the operator to increase flowrates to levels above the flowrate limitations of tools in the downhole tool string, as well as other scenarios which require the flow of fluid to be bypassed around the tool string.

In general, known cyclical bypass valve devices require a deformable ball to activate the bypass valve, allowing fluid to travel around the tool string and within the wellbore. A second, metal ball(s) is then used to close the bypass valve so that fluid again flows through the tool string. Pumping a ball through a pipe or coiled tubing string is a very time consuming process. This is particularly true when pumping the ball through a coiled tubing string where the ball must travel through the entire spool of coiled tubing before it even reaches the vertical column within the wellbore.

SUMMARY

Embodiments described herein are directed to a pressure activated valve assembly that includes a sub, a piston and a biasing member. The sub has a sidewall extending between a first open end and a second open end. The sidewall defines a cavity between the first open end and the second open end and also defines at least one port passing through the sidewall and in communication with the cavity. The sub is configured to allow a fluid to flow through the cavity from the first open end toward the second open end. The piston is disposed at least partially within the cavity and has an orifice through which the fluid can flow. The biasing member exerts a force on the piston directed toward the first open end. The piston is movable between a first position and a second position. In the first position, the piston covers the at least one port, thereby preventing the fluid from flowing through the port. In the second position the at least one port is uncovered and at least a portion of the fluid can flow through the at least one port. The piston is configured to be in the first position when the fluid flows at a first flowrate and in the second position when the fluid flows at a second flowrate. The second flowrate is greater than the first flowrate.

Embodiments described herein are directed to a pressure activated cyclical valve assembly that includes a first sub, a second sub, a piston, and a biasing member. The first sub has a first passageway therethrough. The second sub is coupled to the first sub and has a second passageway therethrough. The piston is positioned within the second passageway and is shiftable between a deactivated position in which a bypass port is closed and an activated position in which the bypass port is open. The piston has a piston orifice and the first passageway is in fluid communication with the second passageway through the piston orifice. The biasing member exerts a force against the piston to maintain the piston in the deactivated position. The piston orifice is sized to restrict the flow of fluid therethrough such that the piston can be shifted between the deactivated and activated positions by changing flowrate of fluid in the first passageway.

Embodiments are also directed to a method of bypassing fluid in a drillstring assembly. The method includes providing a pressure activated cyclical valve assembly in a drillstring, the pressure activated valve assembly includes a sub, a piston, and a biasing member. The sub has a sidewall extending between a first open end and a second open end. The sidewall defines a cavity between the first open end and the second open end and also defines at least one port passing through the sidewall and in communication with the cavity. The piston disposed at least partially within the cavity and has an orifice. The biasing member exerts a force on the piston directed toward the first open end. The method also includes moving the piston from a deactivated position to an activated position by increasing flowrate of a fluid through the cavity and the orifice to increase pressure on the piston to counteract the force exerted by the biasing member and move the piston from the deactivated position to the activated position.

Embodiments also are directed to a method of bypassing fluid in a drillstring assembly. The method includes providing a pressure activated cyclical valve assembly in a drillstring. the pressure activated valve assembly includes a first sub, a second sub, a piston, and a biasing member. The first sub is threadedly coupled to an upper section of the drillstring and has a first passageway therethrough. The second sub is coupled to the first sub and threadedly coupled to a lower section of the drillstring and has a second passageway therethrough. The piston is positioned within the second passageway and is movable between a deactivated position in which a bypass port is closed and an activated position in which the bypass port is open. The piston has a piston orifice, wherein the first passageway is in fluid communication with the second passageway through the piston orifice. A diameter of the piston orifice is smaller than a diameter of the first passageway. The biasing member exerts a force against the piston in a direction opposite the direction of fluid flow through the first and second passageways to maintain the piston in the deactivated position. The method also includes moving the piston from the deactivated position to the activated position by increasing flowrate of a fluid in the first passageway to increase pressure in the first passageway by a predetermined level to counteract the force exerted by the biasing member and move the piston from the deactivated position to the activated position.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the embodiments described herein will be more fully disclosed in the following detailed description, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein:

FIG. 1 is a longitudinal cross-sectional view of a PACV assembly, according to one embodiment described herein, in the deactivated position in which the bypass port(s) are closed.

FIG. 2 is a longitudinal cross-sectional view of the PACV assembly of FIG. 1 in the fully activated or bypassing position in which the bypass port(s) are open.

FIG. 3 is a detail view of an embodiment of a seal insert for use in a PACV assembly.

FIG. 4 is a detail view of a second embodiment of a seal insert.

FIG. 5 is a detail view of a third embodiment of a seal insert.

FIG. 6 is a longitudinal cross-sectional view of a piston, according to one embodiment described herein.

FIG. 7 is a longitudinal cross-sectional view of a PACV, according to one embodiment described herein, employing a deformable plug.

FIG. 8 is a longitudinal cross-sectional view of a piston, according to one embodiment described herein, employing an expandable plug seat.

FIG. 9 is a longitudinal cross-sectional view of a PACV assembly, according to one embodiment described herein.

FIG. 10 is a longitudinal cross-sectional view of a PACV assembly, according to one embodiment described herein.

FIG. 11 is a view of a PACV, according to one embodiment described herein, in a wellbore attached to other downhole tools and in the activated or bypassing position.

FIG. 12 is a view of the PACV of FIG. 11 in a wellbore attached to other downhole tools in the deactivated or running position.

DETAILED DESCRIPTION

This description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. The drawing figures are not necessarily to scale and certain features may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness. In the description, relative terms such as “horizontal,” “vertical,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms including “inwardly” versus “outwardly,” “longitudinal” versus “lateral” and the like are to be interpreted relative to one another or relative to an axis of elongation, or an axis or center of rotation, as appropriate. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The term “operatively connected” is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship.

Embodiments described herein are directed to a pressure activated cyclical valve (“PACV”) assembly that includes one or more bypass ports for bypassing a flow of fluid. In embodiments, the PACV includes a top sub, a bottom sub, one or more bypass ports, a piston, a biasing member, and a seal insert. The top sub is threadedly attached to the bottom sub. The piston is placed within the main bore of the bottom sub and contains seals to close off the downhole section of the apparatus from the bypass port(s). The piston is free to slide within the bottom sub and contains an orifice that is sized to control the fluid flowrate at which the PACV is activated. The seal insert is concentrically placed around the piston, creating a seal between the lowermost face of the top sub and the uppermost shoulder of the bottom sub, disallowing fluid to escape from the uphole section of the apparatus through the bypass port(s). The biasing member is concentrically located within the piston and the bottom sub, and is used to force the piston upwards until the PACV is activated.

During normal drilling or workover operations, fluid, which can be a liquid, gas, or a combination thereof, is pumped and circulated through a downhole tool string. In the event that a portion of the fluid needs to be bypassed around the tool string below the apparatus, the flow rate from the pump can be increased to thereby increase pressure on the piston from the restriction of the orifice, causing the piston to move against the force of the biasing member. The piston will continue to travel until the piston loses sealing contact with the seal insert, thus opening the bypass port(s) in the bottom sub. A portion of the fluid is then free to flow into the wellbore. In this manner, the flow rate of the fluid can be increased beyond the flow ratings of the downhole tools, or the use of heavy drilling mud to “kill” a well, etc.

To close the bypass port(s), the fluid flowrate is reduced below a rate at which the biasing member can shift the piston back upwards to its original position without pressurizing the column of fluid above it. The bore within the top sub and bottom sub in which the piston travels is the same diameter, which allows pressure to balance on either side of the orifice and the piston to travel back upwards under the force of the biasing member. In embodiments, the value of the reduced flow rate can be a preset or predetermined value, which will vary depending on the particular application in which the PACV is employed. For example, the stiffness of the spring and diameter of the orifice can be selected to allow the piston to shift downward at a desired flowrate. This can be dependent on the size of the casing and the capabilities of the pump used. In embodiments, an operator can simply continuously or incrementally decrease the flowrate until the piston shifts back to its the original position.

As the piston travels back to its original position, it reforms a seal with the seal insert, disallowing fluid to escape through the bypass port(s). All circulated fluid now travels through the bore of the PACV, and the PACV is now in its original, deactivated position and is ready to be used again.

If the need arises to completely shut off flow through the downhole tool string thereby bypassing all of the circulated flow, a deformable ball or plug can be used. For example, a complete bypass can be employed when there is a need to pump fluids that would damage the downhole tool string, such as acids or lost circulation material (LCM). Acids can be detrimental to downhole tools so it is generally desired to prevent these chemicals from contacting the downhole tools. LCM contains materials that are used to seal off leaks in wellbores. These LCM materials may be fibers, walnut shells, plastic sheeting, bark, cotton hulls, corn cobs, or any other material that tend to plug orifices or otherwise impair the functions of downhole tools. Thus, in such scenarios, it can be preferable to bypass all circulated fluid into the wellbore while preventing any fluid from entering the downhole tool string.

Once these acids or LCMs are no longer being pumped, an increase in flowrate will force the deformable ball or plug through the piston, and normal operation can continue.

FIG. 1 shows an embodiment of a PACV assembly 5 that can be used to bypass fluid around a tool string and into a wellbore, as needed. The wellbore can penetrate a hydrocarbon bearing reservoir, thereby allowing for the extraction of the hydrocarbon. The apparatus 5 is configured for threaded attachment to a pipe or coil tubing string deployed in a wellbore having a central bore through which fluid can be introduced and flow. In the embodiments illustrated herein, the apparatus 5 is positioned on the pipe string so that it extends longitudinally along the axis of the pipe string to which it is threadedly attached. However, it is contemplated herein that the PACV assembly 5 can be oriented at other orientations with respect to the pipe string and, for example, can be oriented at an angle with respect to the longitudinal axis of the pipe string.

Shown in FIG. 1, the apparatus 5 includes a top sub 20, a bottom sub 25, a piston 30, a biasing member 35, a seal insert 40, and a bearing ring 45. The upper end of the apparatus 5 is referenced by 10 and the lower end by 15. Apparatus 5 is configured for threadable attachment to a pipe string by means of an upper threaded connection 115 of top sub 20. A lower threaded connection 110 is configured on bottom sub 25 for threadable attachment to a BHA (bottom hole assembly). Central bore 135 of top sub 20, central bore 130 of piston 30, and central bores 120, 125, and 140 of bottom sub 25 are all in fluid communication with the central bore of the pipe string. The top sub 20 and bottom sub 25 are threadedly connected via threaded connection 60 of top sub 20 and threaded connection 65 of bottom sub 25. Piston 30 is axially aligned with the tool string and is concentrically located in central bore 120 of bottom sub 25. Piston 30 has seals 50 located about its exterior surface 95 which creates a seal within bore 120 of bottom sub 25. This prevents fluid from the wellbore from flowing around the piston 30 and entering bypass port(s) 90. The seal insert 40 is concentrically placed around the piston 30, creating a seal between the lowermost face of the top sub 20 and the uppermost shoulder of the bottom sub 25, disallowing fluid to escape from the uphole section of the apparatus through the bypass port(s) 90. Seal insert 40 is positioned about piston 30 so that in the deactivated position, as shown in FIG. 1, the seal insert 40 is in contact with the exterior surface 95 of piston 30, thus creating a seal and disallowing fluid to travel around piston 30. Biasing member 35 is located within central bore 125 of bottom sub 25 and central bore 130 of piston 30. In the deactivated position (in which bypass port(s) 90 are closed), biasing member 35 forces piston 30 upwards, until shoulder 75 of piston 30 is in contact with shoulder 70 of top sub 20.

The biasing member 35 can be any element capable of biasing piston 30 toward a given position. For example, the biasing member 35 can be a helical spring, a conical spring, a volute spring, a disc spring, a leaf spring, or any other appropriate spring. Alternatively, the biasing member 35 can be a deformable member such as an elastomeric rod that can deform in response to increased pressure and return toward its original position when pressure is reduced. Alternatively, the biasing member 35 can be an element constructed of elastic or superelastic material that is capable of deforming and storing energy that can be used to translate the piston 30. In such an embodiment, the biasing member 35 can be constructed from an elastomeric material, a silicone material, nitinol or other shape memory alloys, or any other appropriate material. The biasing member 35 can be positioned in any appropriate position within the PACV assembly 5 such that it exerts a force on the piston 30 toward its upward position.

The PACV assembly 5 can be attached to the pipe string and BHA using any appropriate method, including the illustrated threadable engagement. In other embodiments, the PACV assembly 5 can be joined to the pipe string and BHA via bonding, welding, press-fit, snap-fit, or any other appropriate method.

In addition, the top sub 20 and bottom sub 25 can be engaged to one another using any appropriate method, including the illustrated threadable engagement. In other embodiments, the top sub 20 can be joined to the bottom sub 25 via bonding, welding, press-fit, snap-fit, or any other appropriate method.

FIG. 2 illustrates apparatus 5 in the fully activated position, with bypass port(s) 90 open. Fluid travelling downwards from central bore 135 is forced through a smaller sized orifice 80, causing a downward force on piston 30. At a certain flow rate, the downward force on piston 30, caused by increasing pressure from the flow through orifice 80, will overcome the upward force from biasing member 35. Once the downward force on piston 30 overcomes the force from biasing member 35, piston 30 will be forced downward within central bore 120, until shoulder 105 of piston 30 is in contact with shoulder 100 of bottom sub 25. The fluid seal between seal insert 40 and exterior surface 95 of piston 30 will be broken, allowing a portion of fluid from central bore 135 to enter through bypass port(s) 90 and into the wellbore. When there is no longer a need to bypass fluid through bypass port(s) 90 of apparatus 5, circulation through the pipe string is lessened to such a rate that the force from biasing member 35 will overcome the downward force applied to piston 30 by the flow. Hence, piston 30 is forced upwards until shoulder 75 of piston 30 is in contact with shoulder 70 of top sub 20, and apparatus 5 is back in the deactivated position. As piston 30 travels upwards, exterior surface 95 of piston 30 reforms a seal with seal insert 40. As described below, the seal insert 40 can be spring loaded and inner wall 85 of seal insert 40 tapered so that upwards traveling piston 30 can readily reengage seal insert 40, thus recreating a seal between inner wall 85 of seal insert 40 and exterior surface 95 of piston 30.

FIG. 3 shows a detail view of seal insert 40 . . . Seal insert 40 can be made from various materials such as rubber, polyurethane, polytetrafluoroethylene (PTFE), or any other appropriate material. Also, seal insert 40 can be manufactured in a number of ways such as machined, molded, 3D printed, or any other appropriate technique. Seal insert 40 is energized via o-ring 170. The o-ring 170 is positioned in a cavity 86 between an outer wall 84 and an inner wall 85. The o-ring applies a force to inner wall 85 that causes the inner wall 85 to flex inward to engage the piston 30. O-ring 170 can be made from various types of materials such as rubber, PTFE, silicone, or any other appropriate material. O-ring 170 forces inner wall 85 against exterior surface 95 of piston 30, as shown in FIG. 1, to provide compression and form a more reliable seal. Inner wall 85 of seal insert 40 is also shown tapered, which will provide additional compression against exterior surface 95 of piston 30 as piston 30 energizes seal insert 40.

In another embodiment, as shown in FIG. 4. seal insert 150 is energized via spring 175. Spring 175, shown in FIG. 4 as a V-spring, can be of any type of metal or non-metal spring such as a v-spring, coil spring, etc. Spring 175 forces inner wall 145 of seal insert 150 inwards, which provides additional compression to the seal formed between exterior surface 95 of piston 30 and inner wall 145 of seal insert 150.

FIG. 5 illustrates a third embodiment seal insert 155. Seal insert 155 includes a body 156 and a vulcanized seal 180. The body 156 can have a threaded exterior 185 for connection to bottom sub 25. The vulcanized seal 180 can be engaged with the body 156 using any appropriate method including bonding and press-fit. Vulcanized seal 180 can be made from various materials such as rubber, silicone, PTFE, any elastomeric material, or any other appropriate material. Vulcanized seal 180 is a more durable seal than a traditional o-ring seal, and will not be damaged or removed when exposed to high velocity circulation. Seal insert 155 is shown with a threaded connection 185. Seal insert 155 can be secured in place in a number of ways including a threaded connection, set screw(s), pin(s), snap ring(s), press fit, etc.

FIG. 6 illustrates an embodiment of a piston. Piston 160 is threadedly attached to nut 165 via threaded connection 190. Nut 165 can be attached to piston 160 in a number of ways such as a threaded connection 190, set screw(s), pin(s), snap ring(s), press fit, or any other appropriate method. Nut 165 contains an orifice 200, which restricts flow through apparatus 5. At a certain flow rate, a pressure increase from the restriction of flow through orifice 200 will shift piston 160 downwards. Nut 165 can be exchanged to accommodate any sized orifice 200, which will shift piston 160 downwards at a desired flow rate.

In one embodiment, a PACV kit includes a variety of nuts 165, each with an orifice of a different diameter and/or size, thereby allowing a user to select the desired nut at, or near, time of use. The size of the orifice can be chosen based on the viscosity of the pumped material, the length of the wellbore, or any other appropriate parameter.

FIG. 7 illustrates apparatus 5. employing a deformable plug 205 to halt flow through the piston 30. Plug 205 can be made of numerous materials such as Torlon, PEEK, aluminum, brass, rubber coated steel, or any malleable material. Situations arise which make it desirable to temporarily stop circulation through the BHA, such as pumping acid or LCM. In these situations, a deformable plug 205 may be utilized. Deformable plug 205 seats on tapered face 195 of piston 30, forming a fluid seal. A pressure increase above piston 30 forces piston 30 downward against the upward force of biasing member 35. The fluid seal is broken between piston 30 and seal insert 40, allowing all circulated fluid to travel through bypass port(s) 90 and into the wellbore. Once the acids or LCMs are pumped, an increase of flow rate will force plug 205 through orifice 80 and into bottom sub 25. Once plug 205 has been pumped through orifice 80 and a specified flow rate is reestablished, the force from biasing member 35 will shift piston 30 upward until it reforms a fluid seal with seal insert 40 and halts flow through bypass port(s) 90. Circulation is then resumed through apparatus 5 and apparatus 5 is now in the running or deactivated position.

The plugs described herein can be any appropriate size and shape. For example, in one embodiment the plug is a ball having a spherical shape. In other embodiments, the plug can be cylindrical, ovaloid, or any other appropriate shape.

A deformable seat can be used in place of deformable plug 205. As shown in FIG. 6, a separate nut 165 can be attached to piston 160. Nut 165 can be made of various malleable materials such as PEEK, Torlon, aluminum, brass, rubber coated steel, or any other appropriate material. In embodiments in which nut 165 is constructed of a deformable material, a rigid plug can be used to halt flow through the piston. The rigid plug can be constructed of steel or any other relatively rigid material. Once a rigid plug is deployed and circulation of acids or LCMs is completed, an increase of flow rate will force the plug through the deformable seat. Alternatively, both the seat and the plug can be deformable.

FIG. 8 illustrates a second variation of an expandable seat 305 used within piston 300. Biasing member 315, located within bore 335 of piston 300, forces expandable seat 305 upward. Snap ring 320 limits the upward travel of expandable seat 305 within bore 340 of piston 300. Expandable seat 305 comprises at least one split(s) 330 that allow the expandable seat 305 to open and close. Once plug 310 seats against inner face 325 of expandable seat 305, circulation is stopped through orifice 350. Circulation through splits 330 of expandable seat 305 is negligible due to the relatively small area of splits 330. With plug 310 against expandable seat 305, flow through top sub 20 forces piston 300 downward and bypass port(s) 90 are, thereby, opened. Once circulation of acid, LCM, or any other material that the user wishes to bypass is completed, the flow rate through the top sub 20 can then be increased. This increased flow results in an increase in pressure above expandable seat 305 to such a rate that it overcomes biasing member 315, forcing expandable seat 305 downward. Expandable seat 305 then travels downward until it is within bore 335 of piston 300. Bore 335 is a larger diameter than bore 340, allowing expandable seat 305 to open and plug 310 to pass through orifice 350. Hence, material can flow through aperture 345 of piston 300. This decreases the pressure applied to expandable seat 305 and allows the expandable seat 305 to return to its original position within bore 340 of piston 300.

The biasing member 315 can be any appropriate member capable of biasing the expandable seat 305 toward its upper position in bore 340. For example, the biasing member 315 can be a helical spring, a conical spring, a volute spring, a disc spring, a leaf spring, or any other appropriate spring. Alternatively, the biasing member 315 can be a deformable member such as an elastomeric rod that can deform in response to increased pressure and return toward its original position when pressure is reduced.

FIG. 9 illustrates another embodiment of a PACV assembly 210. Bottom sub 245 utilizes at least one shear screw(s) 220 in conjunction with biasing member 35 to retain piston 30 in the deactivated position. The shear screw(s) 220 are engaged with both bottom sub 245 and piston 30 to restrain translation of the piston 30 with respect to the bottom sub 245. At a certain flow rate, pressure increases above piston 30 due to flow restriction from orifice 80 of piston 30. Once the pressure above piston 30 reaches a specified value, shear screw(s) 220 will shear or breakaway and upward force from biasing member 35 will be overcome, forcing piston 30 downward and opening bypass port(s) 90. Once the need to bypass fluid has concluded, the flow rate is lessened to such a rate that biasing member 35 overcomes the downward force and forces piston 30 upward to its original position. Utilizing shear screw(s) 220 can be useful if there is a need to run higher flow rates through apparatus 210. A combination of any number, size, and material shear screw(s) can be useful for exacting a desired shear rate. The shear screws can be fully or partially threaded. Alternatively, the shear screws can be in the form of unthreaded pins. In one embodiment, a single shear screw is used. In another embodiment, two shear screws are used. In another embodiment, four shear screws are used. In another embodiment, between 1 and 4 shear screws are used. In another embodiment, between 1 and 3 shear screws are used.

FIG. 10 illustrates another embodiment of a PACV assembly 215, utilizing piston 160 (as shown in FIG. 3), bottom sub 250 and insert 230. Piston 160 uses an interchangeable nut 165 (as described above with reference to FIG. 6), which allows easy and quick conversions for a desired orifice 200 size, thereby determining the activation flow rate. Insert 230 is threadably attached to bottom sub 250 via threaded connection 235. Insert 230 can be attached to bottom sub 250 in a number of ways such as set screws, pins, snap rings, press fit, or any other appropriate method. Insert 230 can be quickly and easily exchanged to fit the operator's needs. The position of shoulder 260 of insert 230 determines the initial compression of biasing member 35. A higher initial compression rate will require a greater downward force on piston 160 to activate it. Bottom sub 250 utilizes a number of bypass port(s) 285, 290, and 295. As piston 160 travels downwards, the uppermost port(s) 285 are opened first, allowing a specified amount of circulated fluid out at a certain flow rate. As piston 160 continues to travel downward, bypass port(s) 290 are opened, allowing additional circulation to bypass apparatus 215. Once piston 160 has completely traveled downward, bypass port(s) 295 are opened, allowing a larger portion of circulated fluid to bypass apparatus 215 and enter the wellbore. Any size, number, or combination of bypass ports may be utilized in the embodiments described above.

In one embodiment, a PACV kit includes a variety of inserts 230, each with the shoulder 260 at a different height, thereby allowing a user to select the desired compression rate at, or near, time of use. In addition, the size of the orifice can be chosen based on the viscosity of the pumped material, the length of the wellbore, or any other appropriate parameter.

In FIG. 11, the PACV assembly 5 is positioned and threadedly attached to the down hole end 500 of a pipe or coiled tubing string (P) by means of upper threaded connection 24 at the top end 10 of the apparatus 5. A tool string, often referred to as a bottom hole assembly (BHA) is then attached to the PACV assembly 5 by means of threaded connection 23 at the bottom end 15 of bottom sub 25. The sequence of connections of the pipe or coiled tubing string (P) and the bottom hole assembly (BHA) to PACV assembly 5 may be reversed as desired. After such assembly, the pipe or coiled tubing string (P) with the attached PACV assembly 5 and BHA may be inserted into a wellbore (WB) for use. In the configuration shown in FIG. 11, fluid is bypassed around the bottom hole assembly (BHA) and back into the wellbore (WB), as shown by the arrows in the sectioned view.

FIG. 12 shows the PACV assembly 5 inserted into the wellbore (WB) in the same sequence as illustrated in FIG. 11, with apparatus 5 in the deactivated position. As shown by the arrows in the sectioned view, fluid is allowed to flow through the central bore of apparatus 5 during normal operations, as described herein.

In another embodiment, a method of bypassing fluid in a drillstring assembly includes providing a pressure activated cyclical valve assembly 5, 210, 215 in a drillstring. the pressure activated valve assembly includes a first sub 20, a second sub 25, a piston 30, 160, 300, and a biasing member 35. The first sub 20 is threadedly coupled to an upper section of the drillstring and has a first passageway therethrough. The second sub 25 is coupled to the first sub 20 and threadedly coupled to a lower section of the drillstring and has a second passageway therethrough. The piston 30, 160, 300 is positioned within the second passageway and is movable between a deactivated position in which a bypass port 90, 285, 290, 295 is closed and an activated position in which the bypass port 90, 285, 290, 295 is open. The piston 30, 160, 300 has a piston orifice, wherein the first passageway is in fluid communication with the second passageway through the piston orifice. A diameter of the piston orifice is smaller than a diameter of the first passageway. The biasing member 35 exerts a force against the piston 30, 160, 300 in a direction opposite the direction of fluid flow through the first and second passageways to maintain the piston in the deactivated position. The method also includes moving the piston 30, 160, 300 from the deactivated position to the activated position by increasing flowrate of a fluid in the first passageway to increase pressure in the first passageway by a predetermined level to counteract the force exerted by the biasing member 35 and move the piston 30, 160, 300 from the deactivated position to the activated position.

In at least one embodiment, the method further includes equalizing pressure in the first passageway above the orifice with pressure in the second passageway below the orifice such that the piston 30, 160, 300 moves from the activated position to the deactivated position.

In at least one embodiment, the method further includes deploying a plug 205, 310 in the drillstring so that the plug 205, 310 blocks the orifice while the piston 30, 160, 300 is in the activated position. The plug 205, 310 can be made of a deformable material and the method can further include increasing the pressure in the first passageway to move the deformable plug 205, 310 through the orifice and into the second passageway. Subsequently, the pressure can be equalized in the first passageway and the second passageway such that the piston moves from the activated position to the deactivated position.

Alternatively, the piston includes an expandable seat 165, 305 and the method further includes increasing the pressure in the first passageway to move the plug through the orifice and into the second passageway. Subsequently, the pressure can be equalized in the first passageway and the second passageway such that the piston moves from the activated position to the deactivated position.

Although the devices, kits, systems, and methods have been described in terms of exemplary embodiments, they are not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the devices, kits, systems, and methods, which may be made by those skilled in the art without departing from the scope and range of equivalents of the devices, kits, systems, and methods. 

What is claimed is:
 1. A pressure activated valve assembly, comprising: a sub having a sidewall extending between a first open end and a second open end, the sidewall defining a cavity between the first open end and the second open end and also defining at least one port passing through the sidewall and in communication with the cavity, wherein the sub is configured to allow a fluid to flow through the cavity from the first open end toward the second open end; a piston disposed at least partially within the cavity, the piston having an orifice through which the fluid can flow; and a biasing member exerting a force on the piston directed toward the first open end; wherein the piston is movable between a first position and a second position, in the first position the piston covers the at least one port, thereby preventing the fluid from flowing through the at least one port, and in the second position the at least one port is uncovered and at least a portion of the fluid can flow through the at least one port, and wherein the piston is configured to be in the first position when the fluid flows at a first flowrate and in the second position when the fluid flows at a second flowrate, wherein the second flowrate is greater than the first flowrate.
 2. The assembly as recited in claim 1, wherein in the second position, the piston is below the at least one port in the sidewall.
 3. The pressure activated valve assembly as recited in claim 1, wherein the orifice of the piston has a smaller cross-sectional area than at least a portion of the cavity.
 4. The pressure activated valve assembly as recited in claim 1, wherein the piston includes a removable nut defining the piston orifice.
 5. A pressure activated cyclical valve assembly configured to control a flow of a fluid, comprising: a first sub having a first passageway therethrough; a second sub coupled to the first sub and having a second passageway therethrough; a piston positioned within the second passageway and shiftable between a deactivated position in which a bypass port is closed and an activated position in which the bypass port is open, the piston having a piston orifice, wherein the first passageway is in fluid communication with the second passageway through the piston orifice; and a biasing member to exert a force against the piston in a direction opposite the direction of the flow of the fluid through the first and second passageways to maintain the piston in the deactivated position, wherein the piston orifice is sized to restrict the flow of the fluid between the first passageway and the second passageway such that the piston can be shifted between the deactivated and activated positions by changing flowrate of the fluid in the first passageway.
 6. The assembly as recited in claim 5, wherein an increase of the flowrate of fluid in the first passageway to a predetermined level increases pressure in the first passageway sufficient to overcome the force exerted by the biasing member and thereby shift the piston to the activated position.
 7. The assembly as recited in claim 5, wherein the first passageway and the second passageway have the same diameter.
 8. The assembly as recited in claim 7, wherein the piston orifice terminates a tapered passageway that extends between the first passageway and the second passageway.
 9. The assembly as recited in claim 5, wherein the first sub is threadedly coupled to an upper section of a drillstring, and the second sub is threadedly coupled to a lower section of the drillstring, and wherein the drillstring is deployed in a wellbore that penetrates a hydrocarbon bearing reservoir.
 10. The assembly as recited in claim 5, further comprising at least one shear screw coupled to the second sub and to the piston, wherein the at least one shear screw restricts translation of the piston with respect to the second sub, and wherein an increase of the flowrate of fluid in the first passageway to a predetermined level causes the at least one shear screw to breakaway to allow translation of the piston with respect to the second sub.
 11. The assembly as recited in claim 5, wherein the piston includes a removable nut defining the piston orifice.
 12. The assembly as recited in claim 5, further comprising a seal insert, wherein the seal insert is in contact with an exterior surface of the piston when the piston is in the deactivated position, and wherein the seal insert includes an inner wall and an outer wall, wherein the inner wall is tapered and a spring biases the inner wall toward a central axis of the assembly.
 13. The assembly recited in claim 5, wherein the piston includes an expandable seat defining the orifice, wherein the expandable seat is configured to transform from a first configuration wherein the orifice defines a first diameter to a second configuration wherein the orifice defines a second diameter which is larger than the first diameter, such that in the first configuration a plug is unable to pass through the orifice and in the second configuration the plug is able to pass through the orifice.
 14. The assembly of claim 13, wherein the expandable seat is translatable from a first position in which the expandable seat is constrained from transforming to the second configuration to a second position in which the expandable seat is able to transform to the second configuration, the assembly further comprising a biasing member exerting a force on the expandable seat in a direction opposite the direction of fluid flow through the first and second passageways to maintain the expandable seat in the first position.
 15. A method of bypassing fluid in a drillstring assembly, comprising: providing a pressure activated cyclical valve assembly in a drillstring, the pressure activated valve assembly comprising: a sub having a sidewall extending between a first open end and a second open end, the sidewall defining a cavity between the first open end and the second open end and also defining at least one port passing through the sidewall and in communication with the cavity, a piston disposed at least partially within the cavity, the piston having an orifice; and a biasing member exerting a force on the piston directed toward the first open end; and moving the piston from a deactivated position to an activated position by increasing flowrate of a fluid through the cavity and the orifice to increase pressure on the piston to counteract the force exerted by the biasing member and move the piston from the deactivated position to the activated position.
 16. The method of claim 15, further comprising decreasing the flowrate of the fluid such that the piston moves from the activated position to the deactivated position.
 17. The method of claim 15, further comprising deploying a plug in the drillstring so that the plug blocks the orifice while the piston is in the activated position.
 18. The method of claim 17, wherein the plug is made of a deformable material, and further comprising further increasing the flowrate of the fluid to move the deformable plug through the orifice; and then decreasing the flowrate of the fluid such that the piston moves from the activated position to the deactivated position. 